A research program to study the neurochemical basis of communication between the cranial nuclei and pathways from different regions of the central nervous system (CNS) was developed in order to gain knowledge of the central processing of information and its effect on a specific organ or on the behavior of the organism. Our research efforts will be concentrated on the connections between the CNS and the vagal nuclei complex (dorsal motor nucleus, nucleus ambiguus, nucleus of the solitary tract). Neurotransmitters have major effects on the behavior of animals by their action and interaction on various "common final pathways" within the CNS. Communication mediated by chemical synaptic transmission both between central connections and the vagal nuclei and among various components of the nuclei complex has significant effects on the 'message' of the vagus (cranial nerve X). Thus, it is important to learn what compounds are acting as neurotransmitters at these various synapses and what mechanisms are maintaining the "synaptic homeostasis." It is also of primary importance to study how alterations of this homeostasis affect the behavior of the animal in order to suggest possible explanations for disease states. Our studies will include measurement of biochemical parameters for the cholinergic, dopaminergic, serotonergic, adrenergic systems as well as for the amino acid transmitters. Our research will be directed toward the following three objectves: (1) identification of the putative neurotransmitters (excitatory or inhibitory) released from the nerve endings of the central inputs which synapse on the specfic nuclei (DMN, NTS, NA) of the vagal complex; (2) investigation of the central pathways to the vagal (nuclei) complex; (3) correlation of the effect of an altered content of a putative neurotransmtter(s) at synapses on the nuclei of the vagal complex to changes in function of an organ system.